High-Resolution Functional Magnetic Resonance Imaging of the Rat Brain: Mapping Changes in Cerebral Blood Volume Using Iron Oxide Contrast Media

Abstract

Contrast-enhanced magnetic resonance imaging was used to produce high-resolution activation maps reflecting local changes in cerebral blood volume after a simple sensory stimulus, Activation of the forelimb region of the somatosensory cortex was performed in α-chloralose—anaesthetized rats with an electrical stimulus (5 V, 3 Hz) delivered through needle electrodes placed subcutaneously on the left forelimb, A gradient echo magnetic resonance imaging sequence, sensitive to changes in the relative amount of deoxyhemoglobin within the cerebral vasculature, produced a 4.05% ± 1.69% increase in signal intensity. This effect was enhanced with an injection of an intravascular iron oxide contrast agent (Combidex, Advanced Magnetics), resulting in a 9.11% ± 1.52% decrease in signal intensity.